If you're going to add your own instructions anyways, then why go risc-v over arm?
Their success with M1 and M2 aren't hugely generalisable.
Even for RISC, you can buy some boards but I assume those don’t count. But at a regular consumer level, there’s tons of ARM computers in use right now, even if they’re restricted to only a few companies who make them.
I think the same may happen with smartphones/TVs/tablets/etc. Billions of these devices are sold each year, compared to perhaps tens of millions of high-end desktops or servers.
RISC-V I don't know about, but having fixed length instructions is theoretically safer.
If you are thinking of a tower though, there may in fact not be any. That is more of a statement about this desktop market than the RISC one though.
https://cdn.statcdn.com/Statistic/270000/272595-blank-355.pn...
Plum forgot about the iMac.